Dipolar electro-optic compositions and method of preparation

ABSTRACT

Methods and apparatus incorporating suspensions of assymetric minute dipolar particles for the control of electromagnetic radiation. The physical electrical and optical properties of the dipolar particles and their suspending medium are specified in conjunction with apparatus employing them.

nited States Patent 1191 Marks [45] Nov. 20, 1973 [5 BIPOLAR ELECTRO-OPTIC 3,241,948 3/1966 Clarborne et a1. 75 .5 B COMPOSITIONS AND METHOD 01 3,367,766 2/1968 Harrington et al.... 29/192 2,456,313 12/1948 Pratt 106/290 PREPARATION 3,007,160 10/1961 l-lalpem 343/18 [76] Inventor: Alvin M, Marks, 153-16 10th Ave 3,171,106 2/1965 Lemmond 340 174.1 whitestone, N Y 3,213,027 10/1965 Fatuzzo et a1. 252/63.2 3,513,449 5/1970 Young 340/173 [22] Filed: Mar. 3, 1970 2 l N 16 185 OTHER PUBLICATIONS App o" Powder Metallurgy, Goetzel, Vol. 1, lnterscience Pub- Related US. Application Data lishers, Inc., N.Y. pp. 9297 copy in library (1949). [63] Continuation-in-part of Ser. No. 378,836, June 29,

964, Pal 3,512,876 Primary ExaminerJohn D. Welsh AttorneyPhilip D. Amins [52] U.S. Cl. 252/309, 348/18, 106/288 B, 148/16, 252/300, 350/267 [51] Int. Cl B01j 13/00 [57] ABSTRACT [58] Field of Search 252/63.5, 63, 309; Methods and apparatus incorporating Suspensions of 343/18 A; 29/192 R; 75/.5; l48/1.6; 350/267 assymetric minute dipolar particles for thecontrol of electromagnetic radiation. The physical electrical and [56] References Cited optica1 properties of the dipolar particles and their UNITED STATES PATENTS suspending medium are specified in conjunction with apparatus employing them. 2,543,793 3/1951 Marks 350/267 3,151,971 10/1964 Clough 75/.5 B 17 Claims, 69 Drawing Figures PATENTEDHUYZO 1975 sum cu or 9 PAIENIEUnmo I975 v 3.773.684 SHEET NM 29 L/6 7 FIG. 43

INVENTOR. 2' 41/5 ,44 w/v M Mazes Fl G. 42 m 424M161 PATENTEU I975 SHEET 160! 29 3.773.684

FEG. 45 w T rraleA a V PATENIED Hm 20 mm SHEET 180F 29 VARIOUS CROSS SECTIONAL AREAS FOR HALF-WAVE DIPOLE Aa+Ab ZOEbMw mmOmo w C. 4mm

RATIO OF RADIATION RESISTANCE TO ABSORPTION RESISTANCE SIM W W mm VM W m M wf M/ C Q PAIENTED IIIIIZO I873 CURVES OF CONSTANT MINIMUM TRANSMISSION RELATIVE TRANSMITTANC E ELECTRIC DICHROIC RATIO I'o 2b 3b MAXIMUM TRANSMITTANCE vs.

ELECTRODICHROIC RATIO FOR CONSTANT MINIMUM TRANSMITTANCE OF 0.0I%, O. I% AND I% lSUF 29 Z CELL CONTAINING A CHROMIUM DIPOLE SUSPENSION VOLTAGE TRACE IKV/ DIV.

TIME (milhseconds) Z CELL CONTAINING A CHROMIUM DIPOLE SUSPENSION 8 VOLTAGE TRACE lKV/DIV TIME (mllllseconds) 

2. An electrodichroic composition of matter according to claim 1 in which the transparent fluid suspending medium is a thermoplastic medium.
 3. An electrodichroic composition of matter according to claim 1 in which the transparent fluid suspending medium is thixotropic.
 4. An electrodichroic composition of matter according to claim 1 in which the transparent fluid suspending medium has a resistivity of at least 30 megohm-cm.
 5. An electrodichroic composition of matter according to claim 1, in which the conductive particles are selected from the class consisting of aluminum, aluminum nickelide, antimony, cadmium, chromium, copper, gold, indium, lead, palladium, platinum, silver tantalum, thalium, titanium herapathite and tungsten.
 6. An electrodichroic composition of matter according to claim 1 in which the particles are needle-like.
 7. A pigment comprising an electrodichroic composition of matter according to claim 6, in which the dipoles have maximum lengths in the rnage of 1000 to 3000 A.
 8. An electrodichroic composition of matter according to claim 1 in which the particls have a long dimension of the order of lambda /2n, and at least one other dimension not exceeding lambda /10n, where lambda is the wavelength of light in the visual range and n is the indeX of refraction of said transprent suspending medium.
 9. An electrodichroic composition according to claim 5 in which the particles are flakes having long dimensions in the range of 1000 to 10,000 A, and said flakes having thicknesses of 50 to 250A.
 10. The method of preparing a dipolar crystalline suspension defined by claim 1 which comprises forming from solution a suspension of needle-like crystals in a solvent media, saod solution being in at least a saturated condition, adding a miscible non-solvent of higher boiling point to said solution, and thereafter removing the solvent component.
 11. The method of preparing a dipolar crystalline suspension defined by claim 1 which comprises forming from solution a suspension of needle-like crystals in a solvent media containing a polymer, said solution being in at least a saturated condition, adding a miscible non-solvent of higher boiling point to said solution and thereafter removing the solvent component.
 12. The method of preparing a dipolar crystalline suspension defined by claim 1 which comprises forming from solution a suspension of needle-like crystals in a solvent media containing a polymer, said solution being in at least a saturated condition, adding a miscible non-solvent of higher boiling point to said solution and thereafter removing the solvent component, said non-solvent being of a sufficient quantity to form a paste upon removal of the solvent.
 13. The method of preparing a dipolar crystalline suspension defined by claim 1 which comprises forming from solution a suspension of needle-like crystals from a solvent media containing a polymer, said solution being in at least a saturated condition, adding a miscible non-solvent of higher boiling point to said solution and thereafter removing the solvent component by vacuum, said non-solvent being of a sufficient quantity to form a paste upon removal of the solvent, and thereafter adding a low viscosity miscible non-solvent to dilute the paste to form a low viscosity dipolar suspension.
 14. A method according to claim 13 in which the needle-like crystals are Herapathite crystals.
 15. An electrodichroic composition of matter of a high viscosity concentrate including a polymer 1000 parts, plasticizer 1000-5000 parts, dipolar particles 1-1000 parts suspended therein, and said dipolar particles having lengths in the range of 0.1-1 Mu .
 16. An electrodichroic composition of matter including a nonionic fluid containing 1-10 percent of a high viscosity concentrate according to claim 15, with which the polymer and plasticizer is compatible, and dissolved therein, and in which total composition the dipoles are suspended.
 17. An electrodichroic composition of matter comprising a suspension of conductive particles in a non-reactive transparent fluid suspending medium, said particles having lengths in the range of 0.1-0.2 Mu and each of said particles having length to thickness ratios of at least
 5. 